Continuous inductive train-control system



April 23, 1929. c. F. ESTWICK CONTINUOUS INDUGTIVE TRAIN" CONTROL SYSTEI Filed Aug. 5, 1925 Qmwrptoz q 1 Patented Apr. 23, 1929.

UNITED STATES PATENT OFFICE.

YORK.

CONTINUOUS INDUCTIVE TRAIN-CONTROL SYSTEM.

Application filed August 5, 1925. Serial No, 48,313.

This invention relates to train control and more particularly concerns an auton'iatic train control system of the continuous inductive three-position type.

In the three-position type of automatic tru in control systenn influences COIJI'GSPOIlCllIIg to traffic conditions are transmitted to a inovlug vehicle by means of two alternating currents flowing in the track rails. One of these currents, usually termed the t 'ack phase current, flows in the two track rails in series, while the other current termed the line phase or simplex current flows in the two track rails in multiple. The control influences are usually transmitted by cutting otl' the track phase current in an occupied or danger block and by reversing the instantaneous olarity of the line phase current in the first lock in the rear of an occupied block.

In train control installations in congested districts, large variations in the line phase control current-s sometimes occur as a result of stray currents produced in the track rails by differences in ground potentials at various points in a block, these ground potentials being caused by alternating current power lines. by signaling or train control circuits on adjacent trackways, or by other sources of electrical energy. In order to obtain re liable operation of thecar-carried control apparatus, it is desirable to have at least one of the control currents of a constant value, and these large variat-ionsin the line phase current waused by stray potentials are therefore very undesirable.

With the above and other considerations in mind it is proposed in accordance with the present invent-ion to provide a system of automatic train control of the continuous inductive ty )e in which car-carried means are provided or supplying a constant current to the control apparatus, which current corresponds to the frequency and flow of the line phase control current but which does not Vary in amplitude in accordance with variations in the line phase current.

Other objects, advantages and characteristic "features of the invention will be apparent as the description thereof progresses.

In describing the invention in detail, reference will be made to the accompanying drawing, in which a single figure has been shown, representing the car-carried and trackway apparatus of a train control system embodying; the present invention in a simplified and diagrammatic manner.

The present invention adapted for use with many ditl'erent forms of continuous inductive control systems, but the system chosen to illustrate the nature of the invention is of the well known three'position type. As this type of train control system is well known to those skilled in the art, its construction and operation will be very briefly described.

Referring to the trackway apparatus, the track rails 1 have been shown divided into blocks by the insulating joints 2, the block I and the ends of the two adjacent blocks H and J having been shown. As the apparatus and circuits used in connection with the various blocks are substantially identical, corresponding elements will be referred to by like reference characters having distinctive exponents.

An alternating track circuit current, which is also the track phase train control current is impressed upon the two track rails in series at the entrance end of each block by means of the transformer 3 and a circuit which is obvious from the drawings. the usual track reactance 4 being: included in this circuit. An alternating current track relay 5, normally energized by the track circuit current, is connected across the track rails at the entrance end of the block. its local phase being energized by a suitable local source of alternatins: current (not shown). When a train or vehicle is located in the block its wheels and axles shunt the track circuit and track phase train control current from the track rails and cause the track relay 5 at the entrance end of the block to be deeneroized. Line phase or simplex train control current is supplied to the two track rails of the blocks in multiple from the transformer 6. the circuit for this current under clear traffic conditions being traceable as follows :-from the transformer 6, wire 7 contact finger 8 and front contact of the track relay 5, wire 9, balance resistance 10. two track rails of the block I in multiple, balance resistance 11. wires 12 and 13, front contact and contra-t finger 14 of the track relay 5 and wire 15 to the transformer 6. It is obvious that when a train is located in a given blocln say the block J, the track relay 5 at the entrance end of this block is de-enen gized, retraction its contact fingers 8 and 14 This causes a reversal of the instantaneous TO GENERAL RAILWAY polarity of the line phase current supplied to the block I, the path of this reversed line phase current being; obvious from the draw High.

\Vayside si nals of the semaphore, color light or other suitable type may or may not be used in connection with the system of the pre invention, but for the purpose oil illustration, semaphore wayside signals Z have been shown at the entrance end of each bloele their well inrown operating circuits and net ices being omitted tor the sake of simpl it'yin gr the drawing.

deterring; now to the car-carried appara tus. a railway vehicle has been conventionally represented in the block H by the wheels and axles 16, the normal direction oi": traffic being; indicated by the arrow. This vehicle is provided with two sets of inductive receiving coils, the tltl'ili phase receiving coils 17 being mounted in trout oi the leading axle of the vehicle in inductive relation to the track rails, and the line phase receiving coils 18 bein mounted to the rear of at least one of the vehicle a) and preferably to the rear of the locomotive or other equipped vehicle v and in inductive relation to the track rails. The track phase receiving coils 17 are connected through a suitable au'iplitying device AT, preferably of the audion tube type, to one of the windings 19 of a polyphase main relay MR through circuits which are obvious from the draudngs The line phase receiving coils 18 are connected through an amplifier All to a polarized relay P, the output circuit Oil this relay being connected through a transformer 20 to the other winding 21 of the relay MB. The output circuits of the amplifiers AT and All are provided with suitable tuning condensers (T and CL rcsper'itively by means of which the necessary phase relation between the curr-tviti-js in these circuits may be obtained, although the inductanccs ll 45 can be used to obtain this necessary phase relation between currents betore reaching the car.

The polarized relay P comprises a permanent magnet or field piece havi 1" a polarized armature 23 suspendei l between. the pole pieces thereof from the support 24: as shown. A winding .25 is provided on the polar armature 23 being); ctmnected to the output circuit of the line phase amplifier AL through a circuit which is obvious from the drawings. The armature is provided with. two flexible contac Q6 and 527 which are adapted to contact wrh suitable stationary contacts 28 and respectively when the armature 23 is swung to one or the other of its extreme positions. The stationarv contacts 28 and 29 are connected by the wires 30 and 31 respectively to the positive and negative terminals of the battery Blithe n'iidpoint of this battery being connected by a wire 33 to one terminal of the primary winding of the transformer 20, The armature 23 of the polarized relay P is connected by a wire 34- to the other terminal of the prima ry winding' of the transformer 20.

The main relay hill has two movable contact fingers 35 and 36 which operate to control the energization of circuits tor the carearried control apparatus. As the. mriicular torm of control used forms no part of the present invenlioiu and as this control may be obtained in a vari of ways by the use oil. any of a number or illil'tllilc devices-1 well known in tl e art, an extremely simple term of control apparatus has been shown. The control apparatus has been shown as consisting: oi a medium speed brake applying device h ll) and a low speed brain applying device LB, it being assumed that when the device MB is tie-energized the vehicle brakes will be applied until the train has been brought to a suitable medium speed such as forty miles per hour and that when the device III) is dcenergized the vehicle ln-akes will be applied until the vehicle speed has been reduced to a suitable low value, such as fifteen miles per hour.

lab signals oi? any suitable type may or may not be used in connection with the present invent on and in the embodiment shown the cab signals G Y and B representing clear, caution and danger trattic emiditions respectively, have been shown, it being assumed that these signals comprise lights, discs or other suitable ini'lieatingr devices which are displayed when energized.

Operation-All ot' the :uuiaratus and devices shown in the drawing have been shown in their normal operated conditioin that is, with the train prm'eedin r under clear traffic conditions ahead and with all circuits properly energized, For the purpoce of simplify .ing the wiriiu diagrams, the letters B and C have been used to denote the positive and negative terminals of a suitable car-carried source of cnei y, such a storage battery.

Considering first the operation of a train under clear tratlie conditions ahead, assume that the train 16 proceeding in the block H, there bein no other train in either of the blocks I or J. Under these conditions track and line phase train control currents flow in the track rails of the block H and induce voltages in the receiving coils 17 and l8 respectively. The voltages induced in the track phase receiving coil 17 are amplified by the track phase amplifier- AT and impressed upon the winding 19 of the main relay MR. The voltages induced by the line phase control currents are amplified by the line phase aniplifier AL and impressed upon the polarizing winding; oi the polarized relay P. It is assuu'ied that the output circuit of the amplifier AL is arranged to produce an alternating current, and the flow of this alternating current through the polarizing' coil 25 on the polar armature of the relay P causes this armature 23 to vibrate or oscillate between the Dtl lllll llll pole pieces of the permanent magnet 22 according to the usual operation of the polarized relays. The vibration of the aruiature 23 causes current from the battery 32 to be impressed upon the primary winding of the transformer 20. the polarity of this current being reversed in synchronism with the oscillations of the arumture '23. An alternating current is produced upon the winding 21 of the main relay MR through a circuit which is obvious from the drawings. The cnergization ot the windings 19 and 21 of the main relay MR cause this relay to assume its normal position as shown, energizing the medium speed brake applying device MB and the clear cab signal G through circuits which are obvious from the drawings. The low speed brake applying device LB is energized through the contact finger 36 of the main relay and an obvious circuit. Vith the clear cab signal G energized, the engineer is apprised of the fact that he is proceeding in clear territory, and since the brake applying devices MB and LB are energized, he may proceed without automatic restriction so long as clear traffic conditions exist.

Considering now the operation of the apparatus under caution tratlic conditions, assulne that a train or vehicle is located in the block J and that the train under consider:

tion enters the block I in which caution,

traflic conditions exist. The line phase train control current flowing in the track rails of the block I are of reverse instantaneous polarity as compared with line phase control current flowing in a clear block for reasons hereinbefore described. This line phase current of reverse instantaneous polarity operates the polarized relay P in the manner described in connection with operation in a clear block. and produces an alternating current in the winding 21 of the main relay MR which is reversed in instantaneous polarity with respect to the current flowing in this winding when proceeding in a clear block. The winding 19 of the main relay MR is energized from the track phase receiving coils 17 in the usual manner and the main relay, being supplied with current of normal polarity in one of its windings and of reverse polarity in the other of its windings, operates to swing its contact lingers to their reverse position, as represented by the diagonal dotted lines. The energizing circuit for the medium speed brake applying device MB and for the clear cab signal G is broken, and these devices are de-energized, causing a brake application which persists until the vehicle speed has been reduced to the assumed medium Value of 40 miles pc r hour. The caution cab signal Y is energized through the contact finger 35 of the main relay MR and a circuit which is obvious from the drawings. The low speed brake applying device LB is energized through the contact finger 36 of the main relay in its reverse position, and a circuit which is obvious from the drawing. After the train speed has been reduced to the medium value the vehicle may proceed without further restriction throughout the caution block.

As the vehicle passes out of the block I and enters the block J in which a train is located, the main relay MB is (lo-energized due to the fact that no track phase current flows in the track rails of the block J when a train is standing in this block. Lino phase current of normal polarity however flows in the track rails J in multiple and causes the energization of the winding 21 of the main relay MB in the manner described in connection with train operation in a clear block. The de-energization of the main relay MR causes its contact fingers 35 and 36 to assume their de-energized positions as represented by the vertical dot-- ted lines, thus causing the de-energization of the low speed brake applying device LB and the cab signal Y, and causing the energization of the danger cab signal R, the circuits being obvious from the drawing. Die-energization of the low speed brake applying device LB initiates an automatic brake application which persists until the vehicle speed is reduced to a suitable low value, after which the train may proceed at this low speed without further restriction through the danger block.

It is seen that the alternating current supplied to the winding 21 of the main relay MR of a constant value in spite of variations in the line phase current flowing in the track rails, the current in the winding 21 being dependent only on the voltage of the battery 32 which can readily be maintained substantially constant. The alternations of the line phase current are faithfully reproduced by the polarized relay P- in the energizing circuit for the winding 21. so that the influences transmitted from the rackway by the reversal of the instaneous polarity of the line phase current reliably indicates trafiic conditions ahead.

As the present invention has been described in connection with a rather specific train control system including certain specific devices, it should be clearly understood that the invention is not limited to the use of the particular means shown and described, and that various changes, adaptations and modifications may be made without departing from the scope of the invention as defined by the appended claims. For example, the polarized relay P might be replaced by any other suitable means for properly synchronizing the variations of current in the coil 21 of the main relay MR in accordance with the alternations received by the line phase receiving coils 18. a

What it is desired to secure by Letters Patent is 1. In an automatic train control system, in

combinat-ion with an alternating control cur rent of substantially constant magnitude and an alternating control current of varying magnitude flowing in the track rails car-car ried apparatus including a polyphase alternatine current relay, means for supplying an alternating current corresponding in :trequeney to said trackivay control current of substantially constant magnitude to one phase of said relay, and means for supplying a substantially constant currentof a frequency corresponding to said control current of vary ing magnitude, the last said means including contacts operated by an armature for alternately completing circuits of opposite polarity from direct current sources of constant potential to the other phase of said relay.

2. In an automatic train control system, means for transmitting influences corresponding to traflic conditions from the trackvvay to a moving vehicle comprising, an alternating control current of varying magnitude flowing in the track rails, carcarried apparatus including inductive means arranged to have voltages induced therein corresponding to said trackway control current, a polarized relay having an ari'uaturc magnetized by said induced voltages, an electro-rcspensive device, and contacts operated by said armature to alternately close circuits o t opposite polarity including constant sources oi voltage and said electro-responsive device, whereby said electro-responsive device is supplied with an alternating current ot constant magnitude and ot. a frequency corresponding to said tracku'ay control current.

3. In an automatic train control system of the continuous inductive type. the combination with a trackway having! two distinctive alternatin currents: flowing; in the rails thereof, a two-element alternating current relay on a railway vehicle movable over said track- Way, inductive influence receiving means on the vehicle for energizine one element of said relay in accordance with one of said trackway currents, at tuned reed relay vibrated in accordance with tili & alternations of the other (it said trackway currents, and means for applying: current to the other element of said. tivo-element relay in accordance with the vibration ot' said tuned reed relay, whereby variation of magnitude of said other trackivay current when above a certain value does not vary the degree of energization of said two-element relay.

In testimony whereof I attix my signature.

CHARLES F. ESTlVICK 

